Various non-feedback type probing systems have been used in the past, in an attempt to determine the operating voltage or voltages at a given node of the circuit. These non-feedback type probing systems do not dynamically balance an operating voltage, at a node of a circuit, with a voltage on a probe.
An article by the present inventor shows a non-feedback circuit. The circuit is used manually. The circuit is used prior to a probe being connected to a node. The circuit is used to lower transient currents while the probe is being connected to the node. The article is in Electronics magazine, dated Aug. 28, 1980, at page 179.
The present invention improves the balancing capabilities of a circuit probing system. In the present invention, means are provided to dynamically balance a voltage or voltages on a probe, with a voltage or voltages on a node. Means are provided to monitor the output of a circuit under investigation, while the circuit is being probed. Feedback means are provided to continuously adjust the voltage on the probe, in order to accomplish such dynamic balancing. During such dynamic balancing the output of the circuit is in a condition equivalent to its normal unprobed condition. In a dynamically balanced condition, little or no transient current will flow between the probe and the node.